Vanadium Recovery from Bayer Process Liquor Residue

The objective of this work is to develop a vanadium recovery process from a liquor residue of Bayer process. Vanadium finds application in strategic industrial sectors such as steel production and energy storage. The recognized importance of vanadium has pushed academic and industrial research towards the development of technologies for its recovery from different types of secondary sources. The developed process refers to a sodium fluorovanadate sludge from a spent Bayer liquor. The resulting filter cake was characterized to determine its composition and a vanadium recovery process was studied and optimized. This starts with a solubilization of the filter cake by water, followed by a precipitation step of aluminum through pH adjustment with sulfuric acid till 9.2. Vanadium is then recovered as ammonium metavanadate by precipitation with ammonium sulfate using a ratio (NH4)2SO4/salt cake = 2.25 w/w; the precipitate was calcined at T = 500°C to obtain vanadium as V2O5. The results showed an overall vanadium recovery of about 95%, with a purity > 99.6%. The innovative contribution here addressed is represented by the feasibility of producing high-purity V2O5 from the Bayer liquor through a relatively simple precipitation route.